Similar presentations

3 Erosionis a process that wears away surface materials and moves them from one place to anotherAgents of erosion include gravity, water, wind and glaciersWater and wind need to have large amounts of energy to move materialsGlacial erosion moves sediments trapped in the ice by melting

4 DepositionAgents of erosion drop sediments they are carrying as they lose energyEroded sediments are not lost from earthThey are moved by erosional forces and relocated to other areas

6 Mass MovementIs an type of erosion that happens as gravity moves materials down slopeSome are so slow you can’t see them happeningOther happen rapidly and you can seeLandslides are one of the 5 types or a combination of them5 types: slump, creep, rock falls, rock slides and mudflows

7 Slump Is when a mass of material slips down slope as one large mass3 ways this can happen:when a slope becomes too steep and the base can no longer support the sediments aboveWhen water weakens the base and the slipping sediments move downhillStrong rock layer lays on top of a weaker layer and it can not support the strong rock

8 Creep Occurs when sediments slowly shift their positions downhillIs common in places where there freezing and thawing are commonEvidence of creep includes: leaning trees or human-built structures

9 RockfallsHappens when rocks break loose from a steep slope and fall to the groundAs they fall they knock other rocks looseFalling rocks can cause serious damage to structures on the groundThis is caused by the ice wedgingOn roadways signs warn of falling rock areas

10 Rock Slides Occurs when layers of rocks slide downslopeThey move quickly and can be destructiveOccur in areas with steep, mountainous slopesMostly happen after heavy rainfall or during earthquakes

11 MudflowsOccur in places that have thick layers of loose sediments, like soilHappen after vegetation has been removed because of firesWith the lose of vegetation and heavy rainfalls the loose sediments are carried downhill by gravityWhile it moves down slope it gains energy and can destroy anything in its path

13 Preventing Erosion on SlopesBuilding on steep slopes, you must worry about erosionBy building we quicken the process of erosion by removing vegetation and makes slopes steeperThere are ways to prevent erosionBy planting vegetation on slopes we keep soil in place, which reduces the risk of mass movementsConstruction of draining systems prevents water from building up

14 These methods help build a stronger stability of the slopeWe can also help stability by building walls to hold soil in placeLarge amounts of money are spent on trying to prevent mass movementsEarthquakes and rain make it difficult to completely prevent erosion on slopesEventually materials will weaken and gravity takes over causing mass movements

16 Glaciers Glaciers form in regions where snow accumulatesAs snow builds up the weight of snow compresses the lower layers into iceWith enough pressure the mass of ice and snow begins to move, which are known as glaciersAre agents of erosionWhen moving over land they erode, and change features of earthWhile the move the take eroded materials and deposit them somewhere new

17 Plucking Glaciers weather and erode solid rockWhen glaciers melt the water flows into cracks in rocksWater refreezes , expands and pieces of rock are plucked out by the iceDuring this process, boulders, gravel, and sand are added to bottom and sides of the glacier

18 Transporting and ScouringAs the glacier moves large amounts of sediments are transportedSand and plucked rock fragments scour and scrape the soil and bedrockGlaciers cause grooves to form along bedrockGrooves are deep, long, parallel scarsStriations are shallower scarsGrooves and striations show the direction that the glacier is moving

20 Types of DepositsAs glaciers melt boulders, sand, clay and silt are left behindTill DepositsMixture of different sized sedimentsCan cover huge areas of landTill areas in the US span from northwestern Iowa and northern Montana, which are wheat fieldsSome farmland in Ohio contain till depositsRocky pastures of New England have till deposits

21 Moraine DepositsForm at the end of glaciersType of till depositThis deposit doesn’t cover a large area of landMaterials pile up and form a ridge known as a moraineCan also form at the sides of glaciers

22 Outwash DepositsMaterials deposited my the meltwater from a glacier is called outwashCarries sediments and deposits them in layersHeavier materials drop firstCan form a fan-shaped deposit

23 EskersType of outwash depositLooks like a winding ridgeForms in a melting glacier when meltwater forms a river within the iceRiver carries sand and gravel and deposits them within their channel

25 Continental Glaciers Are huge masses of ice and snowAre thicker than some mountain rangesIn the past covered as much as 28% of earthToday they cover 10% of the earthMany of them melted after the last ice age

26 Valley GlaciersOccur in mountains where the temperature is very low all year roundTo find evidence of glaciers look for striations and pluckingThey erode bowl-shaped basins called cirquesArete forms when 2 valley glaciers side by side erode a mountainHorns form when the glacier erodes the mountain from several directionsValleys eroded by glaciers have a U-shape

28 Wind Erosion Wind picks up loose sediments and materialsIt can’t pick up very large sedimentsWind erodes earth’s surface by deflation and abrasionDeflationwind blows across loose sediment, removing small particles like silt and sandLarger materials are left behindOccur mostly in deserts, plowed lands and beaches

29 AbrasionWindblown sediments strike rocks and change the surface and shape of the rocksThe impact of the sand is so strong it breaks off small fragmentsOccurs mostly in beaches, deserts and plowed lands

31 Sandstorms occur when wind blows forcefully in desertsDust storms occur when soil dries outSoil particles weigh less than sand-sized particles and they move higher through the airDust storms can cover hundreds of kilometersBlow soil from places where vegetation has been removed

32 Reducing Wind ErosionPlanting vegetation is one of the best ways to prevent wind erosionFarmers plant trees along their fields to act like windbreaksThe trees reduce the energy of the wind and it is unable to pick up loose sedimentsTree belts also trap snow, which makes the soil more moistMoist soil helps prevent erosion

33 Vegetation is planted along seacoasts and deserts tooGrasses, which have fibrous root systems are the best at stopping wind erosionTheir roots are shallow and twist between particles to hold them in placeplanting vegetation is a good way to reduce the effects of abrasion and deflation, but can’t complete stop it

35 Loess Loess is deposits of fine-grained sedimentsSediments settle on hilltop and in valleysThe particles pack together and create a thick, yellowish depositIs as fine as talcum powderMany farmlands have fertile soil that developed from loess deposits

36 Dunes Dune is a mound of sediments drifted by the windCommon in desert regionsSediments being blown by the wind build up against a rock or bundle of vegetationSide of dune facing the wind has a gentler slopeSide away from the wind is steeperShape of a dune depends on the amount of sediment, wind speed and direction and amount of vegetation present

37 Crescent-shaped dune (barchan dune): open side faces the direction that the wind is blowingThis type of dune forms on hard surfaces where the sand supply is limitedTransverse dune: forms where sand is abundantThe direction of this dune is perpendicular to the wind directionStar dune form in areas where the wind direction changes and form pointed structures